This invention relates in general to hybrid optical devices, and specifically, to a hybrid optical device which includes a filter and a reflective surface in an optical path between at least one input and at least one output.
Optical communications systems are built by combining sub-systems or modules which perform specific networking functions such as removing a single wavelength or group of wavelengths from the complete set of wavelengths (called Add/Drop Multiplexers) or equalizing the optical power level at all the wavelengths (called Dynamic Power Equalizers). A general description of these applications can be found in xe2x80x9cIntroduction to DWDM Technologyxe2x80x9d by Stamatios Kartalopoulos, Wiley-Interscience, 2000. Traditionally such sub-systems or modules are manufactured by integrating several discrete optical components, each of which performs one function, on a printed circuit board or within an enclosure. The large number of such single-function components in each module or sub-system increase the cost, size and optical power loss of these network elements.
There is therefore a need to provide hybrid optical devices in which two or more functions are combined within the same component.
Hybrid passive components are optical components which combine more than one optical function within the same package without converting the optical signal back into its electrical form and without coupling the light multiple times into and out of the fiber. In so doing, they have the potential to reduce the assembly cost, size and optical power loss of network elements. Generally they use some type of free space optical mounting system to insert multiple optical elements between a single set of input and output fibers.
Within Optical Add/Drop Multiplexers and Dynamic Power Equalizers, for example, Applicants recognized that there is a strong need for components which combine the dynamic control of optical power levels by means of a variable optical attenuator, with other functions such as switching, tapping and wavelength division multiplexing. In this way, only a portion of the optical signals will have their power level dynamically adjusted. Applicants recognized that in Switchable Optical Add/Drop Multiplexers and other types of Multiplexers, it is desirable to combine functions using hybrid components that are able to combine two or more of wavelength division multiplexing (WDM) or demultiplexing, attenuation, switching, filtering, tapping and other functions.
A hybrid optical device particularly useful for the above-mentioned applications comprises a filter and a reflective surface, both placed in an optical path between a first set of one or more input optical channels and a second set of one or more output optical channels. The filter passes some of the radiation of the input beam(s) from selected channel(s) of the first set and reflects the remainder. The reflective surface reflects at least some of the radiation that is passed by the filter. The reflective surface or the filter is moved to each of a plurality of positions to perform two or more functions, such as wavelength division multiplexing or demultiplexing, attenuation, switching, filtering, tapping, as well as other functions. Preferably, the optical components of the hybrid device are such that the passage of radiation through the device is non-directional (or bi-directional), so that input channels can become output channels, and output channels can become input channels, whether or not the number of input and output channels are equal.
Preferably, the filter or the reflective surface is moved to the positions by means of an actuator. In the preferred embodiment, the reflective surface and the actuator are provided on a silicon wafer and the actuator includes a plurality of interdigitated fingers. Also preferably, the reflective surface, the filter and the actuator are enclosed by means of a package.